Pneumatic hammer



J. BERNHARD AND A. MEISTER.

PNEUMATIC HAMMER.

.APPLICATFON FILED DIEC- 9. '17919.

1,345, 1 66 Patented July 13,1920.

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swrrZnuLANn PNEUlVIATIC HAD/ [MEB).

Specification lof Letters Patent.

Patented Jury 13,1920.

Application inea December 9, i919. serial no. eraser.

To all Iwhom may concern:

lle it known that we, denon BERNHARD, of l-lasle, near Ruegsau, Switzerland, and nirrnnn Mnrs'rnn, of Ruegsau, Switzerland, both citizens of the Swiss Confederation, and residents of Hasle, near Ruegsau, and Ruegsau, respectively, Switzerland, have invented certain new and useful llmprovements in Pneumatic Hammers,ef which the following is a specilication.

The present invention ,has reference to certain new and useful improvements in power-driven hammers' and relates more particularly to a power hammer, in which the hammer member proper is operated by an elastic liuid, preferably air, which is alternately compressed and rarehed by a powerdriven air pump plunger member, and the speciiic inventive feature is the provision of a working cylinder the upper portion of which, housing the plunger member, is shorter and wider than the lower portion in which the hammer member proper reciprocates,for the purpose of obtaining for the hammer member an operative lift of relatively large' extent than that of the plunger member.

Uur invention will. best be understood when described in connection with the accompanying drawing which shows a vertical section through our improved pneumatic percussive hammer.

llo the wall bracket 1 is secured a perpendicular cylinder 2, formed of a wider upper bore portion 3 and a narrower lower bore portion el, both cylinder portions being superposed in coaxial alinement and the upper wider portion being shorter in extent than Vthe lower narrower portion. ln the bore operates the air pump plunger head 5 to which is imparted a relatively short reciprcoatory movement in the usual manner by means of the cranlr gear 6, 7 of the shaft 8, which latter is journaled in the wall bracket bearings 8 and is provided lwith the fixed pulley 9 and the idle pulley 9 and with theV tly wheel 10. in the lower cylinder bore Ll, closed below by the removable, flanged closure 14, operates the hammer member proper, which comprises the piston head 11, the body member 13 guided in the closure lll, and the hammer head 12. A helical rebound spring 15 is interposed around the body member 13 between the piston head 11 and the cylinder closure 14. rllhis spring 15 serves to lift the hammer member proper immediately after the blow has been struck, aiding Ythereby the Vsuction action of the plunger-member, and Vit is so adjusted that it will normally support the hammer member in its inoperative position about midway of its lift.L i

rlhe plunger member in its reciprocatory operation alternately compresses and rareiies the air within the cylinder above the hammer piston, causing the hammer member to correspondingly reciprocate in an up and down direction, and, the operative diameters of the two cylinder bore portions being different as stated above, obviously theeXtent of the lift of the hammer member will be the larger the greater the relative ratio of the two cylinder portions.

Near its lower end the cylinder bore el is provided with an air port 16 which is controlled by a valve 1T, whereby the cylinder interior below the hammer piston can be brought into or out of communication with the outside air. By adjusting this air valve, which is preferably done before the hammer is started, the power effect of the hammer head can effectively be controlled by more or less throttling down the air in its exhaust from the lower cylinder space on descent of the hammer piston 11. A buffer-spring 18 is interposed between the hammer-head 12 and the cylinder closure 14.

It is clear' that in the described hammer construction with a short lift of the air pump plunger a relatively long lift and thus a correspondingly large power effect of the hammer head will be obtained. .The

`portions differing in length Jand width of Y bore and in unobstructed direct communication with each other, a plunger making an air-tight tit with the widershorter portion of the cylinder, means for reciprocating the plunger in the cylinder, and a hammer member including a piston making an air-tight lit with the'narroiver longer portionv of theV cylinder and being reoiprooable therein by the movement of the plunger.

2. n a pneumatio'hammer of the chaiy acter set forth, ineombination, a cylinder comprising an upper, short and Wide por? tion and a lower, relatively longer and narrower portion, Withboth portions in coaxial alinement, a plunger `member airtightly jit-V Vting said upper oylinder portion, and means v*for reoiproeatmgsaid.plunger member, a

hammer member proper, comprising a pistonhead, a body partand a hammer head, said piston head airtightly operating in said lovver Cylinder portion, means for cushioningsaid hammer member inthe last stage Vber piston.

tion and a lower, relatively longer and narrower portion, With both portions inV oo axialalinement, a plungerl member' airtightly fitting said upper Ycylinder portion, and 'means for reciprocating said plunger member, a hammer member proper, oomprising apiston head, a body part and a hammer head, said piston head airtightly operating insaid lower Cylinder' portion, means for cushioning said hammer in its upward stroke, means for normally returning'said hammer member into its inoperative position, and means for Controlling the powerjefteet of thehammermember proper, comprising an airlvalve near the bottom edge ofsaid lower cylinder portion and operating mechanism therefor, for adjustably throttlng the exhaust air issuingfrom out of the Cylinder interiorbelow said hammer mem- JAKoR BERNHARD. VARTHUR MEISTER. 

